hi and welcome, I am having issues with getting to some of the info I have saved so I will retype some for you....I may forget to add something if I do hopefully someone else will or I'll post more later
first of all what your kitty is going thru is all too common. even tho she is an indoor cat and you don't see any fleas, she still could have been bitten by just one and this will cause what is called Flea Bite Allergy. I can give you a link to that info later, if I can find it...:(
This is also a CLASSIC sign of an allergic reaction to something in your home....is she on dry food??? many chemicals and bad grains that cats can develop a reaction to even if they have been eating same food for years
can also be an Inhaled or Environmental allergy. have you started using more or new chemicals in your home? anything with a scent??? I would discontinue anything...even scented candles/hairspray/room freshners, floor cleaners...USE VINEGAR AND WATER TO CLEAN ONLY. a new laundry detergent??
New rugs or furniture within the last 2-3 months? they spray these fabrics with water repellants and chemicals, that are caustic to pets...and some sensitive people as well
start with eliminating as many chemicals as possible in your home....
slowly transition her over to wet GRAIN free food...this you have to do slowly..for her to accept. If possible try to change the source of protien..ie is she is eating mainly chicken than change it to beef..
NO need for the food to be hypoallergenic like most Vets will tell you...this food is very expensive and most cats hate it
just make sure its grain free...from a good pet supply store not walmarts etc.
get some Omega 3 fatty acids...Krill Oil is the best, pierce the capsule and add to her food IF SHE WILL EAT IT, otherwise will need to put on your finger and than into her mouth, very good for any skin issue
there thats a start....lol
oh...see forgot already. here is a site with some good info on allergy's in cats and dogs too. just disregard what they say abt the hypoallergenic diet...IMO